World Urbanization in 2010 was 51%, and by 2030 this would be around 61%.  Cities in developing countries are expected to absorb 95 percent of urban population growth in the next two decades, increasing the slum population by nearly 500 million between now and 2020.Slums: One billion people live in slums. That’s one out of seven of us. Unless urgent action is taken, 1.4 billion people will live in slums by 2020. Cities account for some 70 percent of global GDP and city slums are often economically vibrant; around 85 percent of all new employment opportunities worldwide occur in the informal economy. Slum-dwellers grew from 777mn to 850mn during 2000-2010. Positive factor: 227 million moved from slums; doubling MDG goals. World needs 4,000 houses an hour to keep up with demand (UN-Habitat)